Jurnal Primatologi Indonesia, Vol. 7 No. 2 Desember 2010, p. 51-54. ISSN 1410-5373. Pusat Studi Satwa Primata, Institut Pertanian Bogor. Javan Surili : A Survey Population and Distribution in Mt. Slamet Central Java, Indonesia
[SURILI JAWA : SURVEI POPULASI DAN DISTRIBUSI DI GUNUNG SLAMET, JAWA TENGAH, INDONESIA]
Arif Setiawan1, Yohannes Wibisono2, Tejo Suryo Nugroho2, Ika Yuni Agustin2, Mohamad Ali Imron1, Satyawan Pudyatmoko1, Djuwantoko1 1Wildlife Laboratory, Faculty of Forestry, Gadjah Mada University, Yogyakarta 2Forest Resource Conservation Departement, Faculty of Forestry, Gadjah Mada University, Yogyakarta Korespondensi: [email protected] Abstrak. Survei ini adalah penilaian yang pertama terhadap populasi dan distribusi surili jawa (Presbytis fredericae) di Gunung Slamet, Jawa Tengah, Indonesia. Survei telah dilakukan selama 150 hari di hutan pegunungan dan menyusuri jalur-jalur yang ada sepanjang 125,38 km. Survey ini telah mencatat 233 individu dari 54 kelompok monyet surili. Metode garis transek telah diterapkan dalam survey ini dan estimasi kerapatan surili jawa adalah 5,6 – 8,16 individu/km2, yang menempati 198.68 km2 potensial habitat. Estimasi populasi surili jawa di Gunung Slamet kurang lebih 1172 – 1621 individu. Perburuan, penebangan liar, pengumpulan kayu bakar, perburuan tanaman hias adalah ancaman yang menyebabkan degradasi habitat surili jawa di hampir semua lereng gunung. Ini adalah sub-populasi terbesar yang tersisa di jawa tengah, jadi perlindungan terhadap Gunung Slamet adalah sangat penting untuk menyelamatkan populasi monyet dan habitatnya, sebagaimana kita ketahui bahwa distribusi sub-species Presbytis di jawa tengah tidak terdapat di dalam kawasan konservasi. Peningkatan status perlindungan hutan, penegakan hukum, program kesadaran konservasi, pemberdayaan komunitas harus didukung dan diteruskan di Gunung Slamet. Abstract. This survey is the ›rst assessment of the population and distribution of the Javan surili (Presbytis fredericae) on Mt.Slamet, Central Java, Indonesia. The survey was carried out for a total of 150 days in the mountainous forest, while walking 125.38 km along existing trails. There were 233 individuals recorded, belonging to 54 groups of monkeys. The line transect method was applied during the survey and it was estimated that there were 5.6 up to 8.16 individuals/km2 density of Javan surili, occuping 198.68 km2, indicating a possible potential habitat. The population of the Javan surili on Mt.Slamet was estimated at approximately 1172 – 1621 individuals. Hunting, illegal logging, fuel wood collection, ornamental forest plants gathering were threats which were the cause of massive degradation of the Javan surili habitat across the facing slope. With its largest sub-population remaining in Central Java, protecting the Mt. Slamet is urgently needed to save this monkey population and its habitat, as it is known that there is no conservation area in the range distribution of Presbytis subspecies in Central Java. Increasing the forest protection status, law enforcement, conservation awareness programs, and community based empowerment should be supported and continued in Mt. Slamet. Key words: rekrekan, surili, Mt.Slamet, population, distribution, endangered
Introduction The javan surili has so far received little attention among researchers and conservationists. Presbytis fredericae Sodi (1930) is found in the Habitat within its distribution range have been central part of Java Island. Until now, the taxonomy threatened by human habitat utilization. While some of this Presbytis is still debated. Presbytis fredericae populations of Presbytis comata in Western Java of Central Java was proposed to be a distinct have already been protected within national parks species (Brandon-Jones 1995, Brandon-Jones et and conservation areas, there are no internationally al. 2004) but another recent study suggested that all Javan surilis should be treated as a single species recognized conservation areas that would protect the (Nijman 2001). This has been followed in the latest surili‘s sub species in Central Java. Only two ›eld assessment on the IUCN Red List, where Presbytis survey and one undergraduate research had been fredericae is treated as a synonym for Presbytis conducted on this species during two last decades comata (Nijman and Richardson 2008). It has been in the central Java region, mainly in the Dieng classi›ed as endangered in the list. Here, Brandon- Mountain area (Nijman 1997a; Nijman and van Jones taxonomy’s was followed in treating javan Balen 1998; Setiawan 2003), where animal density surili (Presbytis fredericae) as distinct species, was estimated to be 28 individuals/km2, and total although it is acknowledged that this should be still population size around 700 – 800 animals. Nijman considered as tentative. (1997a) has visited Mt. Slamet, but population 52 Jurnal Primatologi Indonesia, Volume 7, Nomor 2, Desember 2010, p. 51-54 estimates for this area were not available. This is the Due to the mountainous landscapes and inaccessible ›rst population and distribution survey in Mt. Slamet forest in Mt. Slamet, we established several camps to provide baseline data for further conservation of in the forest. New trails were also undertaken, and the species in Central Java. avoiding trails which were usually used for climbing the mountain due to the high intensity of human Methods activities. There are several villages that we used as This study was carried out in Mt. Slamet, main camps during the ›eld work such as at Curug Central Java Province, Indonesia, the second Cipendog on the south-west slope, Curug Gomblang highest mountain in Java, with an average rainfall and Pancuran Pitue on the southern slope, Gunung of 5000-6174 mm/year and a temperature of 20- Tukung and Gunung Malang on the north-east 30 oC (Central Java Forestry Agency 2010). Even slope, and Gunung Suci on the north-west slope though there are no available speci›c assessments of Mt. Slamet (Figure1). The line transect method on habitat, observation on the changing habitat are was applied (NRC 1981 and Whitesides 1995) to based on vegetation composition along gradient estimate the density. The surveys were done by elevation of Mt. Slamet. Secondary species such walking slowly (1 km/hour), and stoped for several as Macaranga sp., and Trema sp. are dominates minutes to locate branch shaking and sounds of the at the elevation 800 m asl up to 1000 m asl, and monkeys. A local guide and two observers walked mountainous tree species belonging to Fagaceae together, while most of the ›eld work started at 06.00 family such as Quercus and Lithocarpus are the till 17.00, with a break at noon (12.00 till 14.00). dominant species in elevation between 1000 up to The number of individuals, age class, and distance 2500 m asl . of monkey to observer were recorded in prepared The main method for this survey was as silent worksheets. GPS was used to record points where as possible walking and waiting in the forest, mostly the monkeys were seen. The behavior of the primates on the forest trails established by local villagers. were observed ad-libitum, food items consumed by
Figure 1. Study site and trails walked in Mt.Slamet Setiawan et al., Javan Surili : A survey population and distribution 53 the monkeys as food resources were recorded by (Agathis and Pinus), where food resources was not their vernacular name. Data were collected during higher than in the natural forest. This was observed each month in June 2005, August 2006, December at the old forest plantation (more than 20 years old) 2006, November 2007 and February 2008, and ›eld where food resources such as liana, and strangling surveys were done in 150 days. ›gs, were available among plantation trees. Local people around Mt. Slamet actually Results and Discussion recognized all the primates in their forest, Rekrekan A total of 125.38 km of forest trails were walked is the vernacular name for the javan surili, owa in Mt. Slamet. The survey results are presented in for javan gibbon, lutung for the javan silvered leaf Table 1 (Density estimate, efforts, group size of monkey/javan langur, and kethek for the longtailed Javan surili in four different locations in Mt. Slamet) macaque. It is recognized that these primates are separately for each of the four localition. Altitudinal protected by Indonesian law, however enforcement distribution of Presbytis fredericae in Mt. Slamet are still to be concerned. Hunting for javan surili varied between 750 m asl to 2500 m asl, the largest occurred, eventhough not speci›c to ›nd the group size were 14 individuals found at the eastern primates, and it seems to tend to opportunistic slope of Mt. Slamet, while the smallest group size hunting, where hunters who were not ›nding any were 2 animals. Correlation test on the number animals, would catch any animals, whatever they of individuals and elevation showed negative got. A case of hunting occurred during ›eld work relationship between abundance along elevation at the eastern slope of Mt. Slamet, where the javan gradient of Mt. Slamet, however these were not surili was shot and eaten for the meat. Hunting for signi›cantly different (rho : -0.162, S = 25686.50, pets was also recorded based on interview with p-value = 0.2552). villagers at the southern slope of Mt. Slamet, but Nevertheless, the taxonomic debate on the this trade can’t be found in the open market, and Javan surili in Java, information on population only an order by a buyer from the nearest city such and distribution are the most essential data for as Purwokerto. A juvenile javan surili was sold for conservation of this endangered leaf eating monkey. 250,000 IDR. Our density estimation was 5.6 individuals/km2 Habitat degradation have obviously happened at the southern slope and 8 individuals/km2 at at all slopes of Mt. Slamet. Forest plants hunters the eastern slope of Mt. Slamet. These densities by villages looking for ornamental plants such as were lower than in Mt. Dieng, 28 individuals/ orchids and pitcher plants causing a lot of forest trees km2 (Nijman and Van Balen 1998), while previous that were cut down. Illegal logging happened more Presbytis survey in Java recorded 25 individuals/ seriously at the southern slope of Mt. Slamet, not km2 in Mt. Gede (Sujatnika 1992) and 11 only for villagers building materials but also some individuals/km2 at Kamojang (Ruhiyat 1983 in of the illegal loggers selling the logs commercially. Nijman 2001). The distribution occupied not only At the eastern and western slopes of Mt. Slamet at the edge but also inside the forest, and probably it was observed that during the dry season people due to vegetation as food resources are changing were more active to go into the forest for fuel along gradient elevation, the density also appeared wood collection. Confiicts between monkeys and lower at higher elevation. Negative correlations was villagers were recorded at the eastern slope where shown on higher elevations of Mt. Slamet and the the monkeys foraged in vegetable ›elds to ›nd monkey abundance was also decreasing, probably food such as cassava, and other fruits and vegetable due to habitat and environmental factors such as plants, while at the southern slope there were groups temperature, humidity, air stream are diversity along foraging in plantation. It has been noted that these gradient elevation of Mt. Slamet. The monkeys monkeys also become crop raiders (Marchal and also can be found in the habitat of forest plantation Hill 2009).
aTable 1. Density estimate, efforts, group size of Javan surili in four different locations in Mt. Slamet Distance # Groups / individuals Group size, Density Location, Year walked (km) encountered (average, range) (indv/km2) Curug Cipendog, 2005 36.65 13 / 80 6.1 (2-6) 5.9 Curug Gomblang, 2006 39.36 22 / 65 2.9 (2-7) 5.6 Gunung Malang, 2007 16.04 7 / 39 5.6 (2-14) 5.9 Gunung Tukung, 2008 33.33 12 / 49 4.1 (2-6) 8.16
54 Jurnal Primatologi Indonesia, Volume 7, Nomor 2, Desember 2010, p. 51-54
Conclusion Marchal V, Hill C. 2009. Primate crop-raiding: A study of local perceptions in four villages Landsat 2001 satellite imagery analysis was in North Sumatra, Indonesia. Primate used to assess area of the remaining habitat for Conservation. 24:107-116. Javan surili in Mt.Slamet. Which was and there National Research Council. 1981. Techniques are approximately 198.68 km2 for potential habitat, for The Study of Primate Population Ecology. with range density 5.9 - 8.16 individuals/km2 Subcomitee on conservation of natural for population estimation, while a rough number populations. Committee on Nonhuman primates would be 1172 – 1621 individuals in the whole Division of Biological Sciences Assembly of Mt. Slamet. However, it should be noted that of Life Science National Research Council. maybe individual density will vary based on habitat National Academy Press. Washington D.C. chance on the elevation. Thus more detailed Nijman V, Richardson M. 2008. Presbytis comata. studies are needed the largest sub-population may In: IUCN 2010. IUCN Red List of Threatened be remaining in Central Java. Therefore protecting Species. Version 2010.4.